APPENDIX II 295 



the eye itself, but there it changes into the black brown 

 granules above described. 



These " eye-pigment ' granules certainly appear to be 

 very primitive formations. The utilisation of excretory 

 matter as pigment is at once suggested, the incrustation of 

 brown stuff round the nucleus reminding one forcibly of 

 the incrustation of excretory matter round the blood cor- 

 puscles under the dorsal organ (see Appendix IV.). In the 

 pigment granules, however, it was quite regular, whereas 

 it was irregularly massed around the blood corpuscles. 

 These corpuscles, again, are very much larger than the 

 pigment-forming granules, and moreover fairly uniform in 

 size, whereas the latter are of all sizes. 



